The present invention is related to the electrochemical sensing of analytes in a medium or a vacuum, such as odors, smells, vapors and the like in air, and in particular, to methods of determining or resolving such analytes once detected.
There has been considerable interest in developing devices for the general detection of analytes in a fluid, vacuum, air, or other medium. A specific instance of an analyte detector is a device for sensing smells or odors (i.e., analytes in air). It is well recognized that some animals, such as dogs, have a much keener sense of smell than human beings. Because of the acuity of their noses, dogs have been utilized for many tasks including, for example, the detection of bombs, mines, drugs, poison gases, and illegal contraband; dogs also aid in the search and rescue of humans. Devices for sensing smell would be useful for the applications where animals are traditionally used, as well as for a multitude of uses where animals are impractical or inappropriate.
Moreover, devices for the general detection of analytes have potentially many more applications than devices for detecting only smells and odors. For example, the uses for devices for analyte detection include the detection of chemical leaks, quality control in food processing, medical diagnosis and testing, fabrication and manufacture of commercial and industrial goods, pharmaceutical production, testing or evaluating any odorant or analyte in any medium (e.g., fuel, oil, wine, solvents), and many other applications. An instrument for analyte detection would be highly desirable in many industries and applications, such as the chemical, petrochemical, food, fragrance, medical, automotive, military, environmental, health and safety, and air quality monitoring sectors. Therefore, it is desirable to develop techniques and devices for the detection of analytes.
One approach for sensing analytes is the use of an array of sensors on a substrate. Each sensor has a chemical compound which has a particular electrical characteristic response to exposure to an analyte, such as an odor. The sensors are connected to electrical circuits by which the responses of the chemical compounds to the analyte are retrieved. See, for example, U.S. application. Ser. No. 09/130,775, entitled xe2x80x9cSENSOR ARRAYS ON AN IC FOR ANALYTE DETECTION,xe2x80x9d filed Aug. 7, 1998 and assigned to the present assignee, and which is incorporated by reference herein. Each site responds to a broad class of stimuli, with the collective response of the many different members of the sensor array providing a fingerprint of an analyte of interest. The number of data points generated for each analyte is large. Even with modem high-speed computers, the amount of data generated may significantly slow operations to analyze the sensed analytes under real world constraints, in particular. Therefore, there is a need for techniques and systems which are computationally efficient in determining or resolving an analyte upon detection from the large amount of data derived from the sensor array.
The present invention is directed toward such a technique and system for quickly and efficiently resolving analytes. A quantitative metric is generated for the effective resolution of different analytes by the sensor array. The present invention further provides a powerful tool in the analysis and construction of olfactory sensor arrays.
The present invention provides for a method for distinguishing different odors by the steps of disposing a plurality of d sensors in an array, each sensor having different electrical responses to different orders; exposing the sensors to first and second odors; generating first and second sets of data points from each of the sensors, each set corresponding to the first or second odor, each data point being represented by a vector in a d-dimensional space; determining an axis in the d-dimensional space, the axis having the property that projections of the data points onto the axis in the d-dimensional space have optimal separation; and resolving the first odor from the second odor by the separation.